Clay decolorizing of solvent refined lubricating oils



y 1, 1952 G. LUPFER ETAL 2,602,044

CLAY DECOLORIZING 0F SOLVENT REFINED LUBRICAT ING OILS Filed April 7, 1948 FIG. I.

- JNVENTOR. GEORGE L. LUFFER, RALPH c. ATKINSON 2.

BY JOHN D STUBBS Z0183 V 7 Patented July 1, 1952 CLAY DECOLORIZINGOF SOLVENT REFINED LUBRICATING OILS George. L. Lup'fer, Bcdford, Ralph G. Atkinson,

Maple Heights, and John D. Stubbs; Cleveland,

Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio Application April 7, 1942;. Serial No. 19,534

1 Claim. ((1196-1415) refining-process and quite independent thereof.

An objectionable feature of the conventional systemofclayvdecolorization is that since the clay, acts moreefficientlyon oil at a fairly high temperature, it is usually necessary to provide heat exchangers and other means of" raising thetemperature' of the refined mineral oil at the time it 'is clay treated; The" requirement for heat may be a considerable partof the cost of the decolorizirig step. e r V v I These disadvantages of the prior art are over come'in accordance with the invention bythe addition of a solvent toa lubricating oil stock or constituent such as mineral oil,' wax and impurities or mixtures thereof, removing an impurity; or unwanted component, passing the mixtureofoiTStock and solvent to 'amixing tank where decolorizing clay or earth of an appropriate type is added. The resultant-slurry is then heated and the solvent is distilled off. The temperature necessary to distill the solvent is sufficient to efiect good decolorization with a minimum amount of clay. The slurry new consists of an oil stock and clay and is pumpedto' another vessel at which point a second solvent isadded, The eifect of the second solvent is to cause the. removal of another impurity or unwanted component. This leaves a slurry consisting of purified decolorized oil and solvent in one phase and decolorizing clay and second impurity in other phases. It will be understood that the term impurity is used broadly to refer to substances that are undesirable in lubricating oils and th'at'said impurities may be, as in the case of wax, valuable by-products of the process. The clay'and other solids are then removed by an appropriate method such as filtration and the liquid solvent-oil stock mixture passed to another column where the solvent is distilled off. The clay may then be recovered by filtration, distillation or any appropriate means if the impurity is to be recovered.

The fact that the decolorizing clay is mixed with the 011 while diluted with'a solvent and while distillation is being'performed on it, as- Sum'saLdegree of contact between the clay'i'and oil that results in better clecolorization." The high temperature at'which these operations are carried out increases the degree of decolorization produced by a. given amount of clay and since the slurry mustbe heated for the distillation, the separate heating oi, the oil during conven tional decolorization is eliminated. In thisway no additional heat is required and the heat serves two functions; to accomplish the distillation and to decolorize at the same time.

The presence of" the clay in admixture with the first Solvent does not interfere with the solvent removal, and the presence of the clay in admixture with the. second solvent does not adversely affect the removal of the. second impurity.

The process of the invention also has the advantage of avoiding any separate clay removal step after the decolorization, a step which is s ry in t pr or ar af r c ay tr a ment, because the clay is separated simultaneously with the second impurity and by the same step necessary'for separating the second impurity.

The invention will be illustrated by the following examples inwhich reference will be. made to the accompanying diagrammatic drawing:

Example I A clean lubricating oil feed stock containing material removed from the oilchargeds-largely aromatic in character and some leaves themtractor at 3 usually with some solvent and] passes to a separate solvent recovery system; This step is conventional in the art and any of the known solvent extraction procedures may be-used, it may be a batch or continuous process. The rafiinate and the dissolved furfural leaves the extractor section at 4 and enters the-mixing tank i. Decolorizing clay or earth is added to the mixing tank from a bin 5 through automatic clay feeder 6. The amount of clay used may be from .5 to 99 pounds per barrel of soivent-free oil. The clay is maintained in a state of suspension in as shown;

The slurry of raft-mate, furfural, and clay then pumped'througha heat exchanger .or. oil

heater 5 into the raflinate stripper tower 9. The

temperature of the stream entering the'raffinate stripper will be from 400 F. to 550' F, depe nd i rf1 ;g'

upon the type of stool: bein Processed and the pressure. The raifinate stripper in this particular case is operated at a pressure of 0 to 4 pounds per square inch gauge pressure. The furfural is this tank by means of a mixer separated by steam stripping and leaves the tower at I0. Part-of therecovered furfural may be returned to the tower as reflux, and heat may be 7 applied at the bottom of the tower by any means known in the art.

Under the temperature conditions existing in A solvent mixture of methyl-ethyl-ketone, benzol and toluol is added at I3. This dewaxing solvent may be added in a ratioof solvent to oil of from 1:1 to 30:1. The solvent may vary in composition from 10 to 90 volume percent methyl-ethylketone, from to 80 volume percent benzol and from 0 to 80 volume percent toluol. Within unit I2, the oil,.solvent, clay slurry is cooled by any appropriate means such as by ammonia in a double pipe direct expansion system. Under the temperature conditions selected and with the amount of methyl-ethyl-ketone employed the wax in the stock is largely insoluble. The chilled mixture containing the precipitated wax goes to a'filter within unit I2 where the clay and wax are separated from the decolorized oil. This mixture of solids leaves the dewaxing unit at I4, from which theclay, the decolorized wax and the entrained solvent may be separated and reclaimed by any means convenient.

The oil is pumped through heat exchanger I to a methyl-ethyl-ketone solvent recovery system I6-,.the recovered methyl-ethyl-ketcne solvent leaves at IT and the refined, dewaxed and decolorized oil product leaves at I8.

, In this example other refining and dewaxing solvents may be used in a similar sequence.

Example 2 Referring to the same diagram that illustrated Example 1, an oil stock containing an undesirable asphaltic impurity is mixed with liquid propane infa propane oil ratio varying from 1:1 to :1. In the extractor E, the asphaltic material separates out and is removed at 3. The deasphalted oil and solvent now pass through pipe 4 to mixing tank I where clay is added as in Example 1. The amount may vary from 1 to. 150 pounds of clay per barrel of deasphalted oil. After passing furfural is added at I3 in the ratio of from 1:1

to 10:1 depending on the degree of refining desired. The clay is contained in the extract phase which leaves the extraction unit at I4 whence it passes to suitable equipment for the recovery of the solvent, and if desired the separation of the extra-ct from the clay. The oil, now decolorized and free of asphaltic and aromatic material, passes through a suitable heat exchanger I5 to solvent recovery system IB with the recovered In practice the unit at 9 may com- 4 furfural'leaving at I1 and the productat I8. If desired the clay may be separated with'the prodnot at I 8 instead of at I4, and then filtered.

Example 3 Examples! The first solvent added is propane and the first impurity removed, asphalt. The second solvent is methyl-ethyl-ketone and-the second impurity a wax of improved color. The product is a deasphalted, dewaxed and decolorized oil.

Example 5 The first solvent is methyl-ethyl-ketone and the first impurity removed, wax. Appropriate changes in the apparatus may be made so that the wax may be removed at 3. The second solvent is furfural and the second impurity -is aromatic-containing extract. The product is a dewaxed, extracted and decolorized oil.

It should be understood that the above examples merely illustrate the applications of the inventions and are not intended to limit it as to solvents to be employed or impurities to be removed. It will also be understood that changes in operating conditions necessitated by the use of other solvents may be made without departing from the spirit of the invention; The arrangement. of heat exchangers and other auxiliary equipment may also be changed to suit particular operating conditions without departing from the spirit of the invention. The scope of the invention is not limited by the type of decolorizing earth or clay employed as the process is applicable to anyflgranular' decolorizing and said methyl-ethyl-ketone, and subsequently separating said methyl-ethyl-ketone to produce a refined, dewaxed and decolori'zed'oil.

GEORGE L. LUPFE'R.

RALPH G. ATKINSON. JOHN. D. STUBBS.

xEFER Ncns CITED.

The following referencesareofrecordln the file of this patent:

UNITED STATES PATENTS Number Name Date 1,509,326 Weir Sept. 23, 1924 2,145,784 Anderson et. al. Jan.- 31, 1939 2,165,638 Manley July 11, 1939 2,279,937 Brown. Apr. 14, 1942 

